1. Field of the Invention
The present invention relates to a fastening device or fastener, such as a screen hanging fastener for connecting a curtain rail and various hanging screens such as a curtain, or an interior finish material fastener interposed between a mounting member such as a ceiling, a floor surface or a panel of the room interior, and a plate member such as a mat, a carpet, a wall covering material, a ceiling covering material or a dashboard for securely attaching the mounting member and the plate member.
2. Description of the Prior Art
Most curtains used in hospitals and hotels are held under a lease and they are replaced and laundered periodically. To improve the efficiency of the curtain replacement work, an appropriate measure should be taken to facilitate the attachment and detachment of curtains. To cope with this requirement, Japanese Utility Model Laid-open Publication No. HEI 4-104909, for example, discloses a prior proposal made to enable easy attachment and detachment of a curtain relative to curtain runners mounted on a curtain guide member, such as a curtain rail or a guide bar. A screen hanging fastener according to the prior proposal is composed of a plate-like fastening device made from a synthetic resin and including a number of hooks arranged in a plurality of rows and integrally molded on the face of a base member, and a metal hook portion formed from two metal wires and integrally molded in an upper portion of the base member for releasable engagement with a curtain runner. The hooks are molded such that they are aligned in the vertical, horizontal and diagonal direction and form a plurality of rows of hooks arranged in the widthwise direction of the fastening device. The hooks in each hook row are aligned with an axis of the hook row and have the same direction of bend or hook (hereinafter referred to as "hook direction"). The hooks in each pair of adjacent rows have either the same hook direction, or alternatively opposite hook directions. In the fastening devices of this type, in order to support a curtain in a vertically suspended condition, the hooks in the most part of the hook rows generally have a hook direction facing upwards, as shown in FIG. 10(A), to secure a desired fastening strength.
On the other hand, to various mounting members, such as a ceiling, a floor surface and a door panel of an automobile, and a wall, a ceiling and a floor surface of a building various interior finish materials are attached mostly by use of a surface-type fastener generally known as "hook-and-loop" fastener. Male and female fastener parts of the surface-type fastener are attached to the mounting member and the interior finish material, respectively, and vice versa, by means of ultrasonic welding or pressure-sensitive adhesion bonding. However, due to insufficient durability and bonding strength, there has been used a fastening device of synthetic resin which includes a number of hooks projecting from the face of a plate-like base member, and a stud-like projection disposed on the back of the base member and having a resilient locking head portion provided with a pair of wings. The resilient locking head portion is resiliently deflected as it is forced into a hole in the mounting member. When the resilient locking head portion moves past the hole, it springs back into the original shape so that the mounting member is firmly gripped from its face and back sides between the base member and the resilient locking head portion of the fastening device.
Known interior finish material fastening devices of the type described are disclosed, for example, in Japanese Patent Publication No. SHO 51-651, Japanese Utility Model Publication No. SHO 54-26089 and Japanese Utility Model Laid-open Publication No. SHO 57-31250. As is understood from these publications, these fastening devices are widely used not only in the automobiles but also in the interior finish work of buildings. Furthermore, in one form of application proposed recently in Japanese Utility Model Laid-open Publication No. HEI 3-21285, the resilient locking head portion of the fastening device is used as a runner for curtain rail.
In the interior finish material fastening devices or fasteners of the type described, in order to avoid producing the directionality in the fastening strength, the face of the base member is generally separated into a plurality of blocks each including a plurality of rows of hooks arranged such that the hooks in each hook row have the same hook direction, the hooks in the adjacent hook rows have opposite hook directions, and the hook direction of one hook block is perpendicular to the hook direction of an adjacent hook block.
The screen hanging fastener disclosed in Japanese Utility Model Laid-open. Publication No. HEI 4-104909 is advantageous in that since a fastener piece having on its face side a number of hooks is a molded product, the fastening strength of a surface-type fastener can be increased to such an extent much greater than that obtained by conventional hooks formed by weaving or knitting a monofilament. However, a drawback is that the metal hook portion requires a manufacturing process to be achieved separately from the molding of the screen hanging fastener. In addition, the injection-molding process is rendered complicated by the metal hook portion because the metal hook portion must be inserted in a portion of the molded product. From the viewpoint of final products, the metal hook portion increases the product cost. In addition, since the curtain runners are mostly made from synthetic resin, they are likely to be severely worn away by the metal hook portions and hence cannot withstand a long period of use. Furthermore, the metal hook portion and the synthetic resin fastener piece which are made from different materials are not well-matched in appearance and cannot readily be chromatically coordinated under the same color tone.
In the case of the interior finish material fastener, the stud-like projection is forced into the hole in the mounting member against the resiliency of the winged interlocking head portion. When the head portion is moved past the hole, the winged interlocking head portion springs back into its original shape with the result that the mounting member is gripped from its face and back sides between the plate-like base member and the winged interlocking head portion. In this instance, if the back side of the mounting member is irregular due to the presence of a burr or projection which may be produced at the time of forming the hole, the interior finish material fastener might be incompletely attached to the mounting member, with the winged interlocking head portion left within the hole due to interference with the burr or projection. With this incomplete attachment, an interior finish material attached via the interior finish material fastener to the mounting member is easily detached from the mounting member when it is subjected to a force tending to separate the interior finish material and the mounting member. This deficiency may be overcome by providing a space between the base member and the winged resilient interlocking head portion, which space is equal to the sum of the thickness of the mounting member and the height of the burr or projection. The space thus provided, however, would cause a problem that when the back side of the mounting member is flat at least in an area around the hole, the interior finish material fastener is freely movable in the axial direction of the hole within some distance, thus producing wobbling between the mounting member and the interior finish material.
In the aforesaid prior screen hanging fastener, the hooks in the plural hook rows are all directed upwardly. On the other hand, in the aforesaid interior finish material fastener, the hooks in the plural hook rows (about 1/2 of the whole hook rows) are directed inwardly of the peripheral edge of the base member.
Regarding the screen hanging fastener, the weight of a curtain is mostly born by these hooks which are disposed along a lower edge of the screen hanging fastener. These hooks are subjected to a greater load than other hooks and hence they are gradually fatigued by repeated curtain attachment and detachment operations. Eventually, when the curtain is peeled off from its top edge, hooks in the lowermost tier and hooks in the second tier from the bottom as well are liable to be broken, as shown in FIG. 10(A). This is because due to the absence of the hooks and the base member which support or back up the hooks against bending, the hooks in the first and second tiers from the bottom are bent to a greater extent than other hooks and hence are susceptible to fatigue and breakdown.
In the case of the interior finish material fastener, a mating fastener member is supported mainly by these hooks which are disposed along the peripheral edge of the base member, as shown in FIG. 10(B). Consequently, these hooks are liable to become fatigued to a greater extent than other hooks when they are subjected to a repeated load. When the mating fastener member is separated from the interior finish material fastener, the mating member is progressively peeled off from the peripheral edge toward a central portion of the base member. Since the hooks in the hook rows have a direction facing inwardly from the peripheral edge of the base member, as shown in FIG. 10(B), they are only able to show a limited or relatively low peeling resistance at the initial stage of peeling or separation. The peeling strength of the overall fastener is reduced, accordingly.